GSM ► Engineering Materials ► Plaster of Paris & Acoustic materials

What is Plaster of Paris?
How do you make it? Homemade

PLASTER OF PARIS Recipe Plaster of Paris is a Calcium sulfate semi-hydrate (CaSO4, 1/2 H2O) derived from Gypsum, a calcium sulfate di-hydrate (CaSO4, 2H2O), by firing this mineral at relatively low temperature and thus reducing it to powder. CaSO4, 2H2O + HEAT -----------------> CaSO4, 1/2 H2O + 1.5 H2O In 1700’s, Paris was already the “Capital of plaster” since all the walls of wooden houses were covered with plaster, as a protection against fire. The King of France ► enforced rule ► after the big fire in England 1666. Large Gypsum deposits near Paris ► mined ► manufacture of Plaster of Paris

Items Needed (Apparatus) to make plaster of paris with glue

• 2 parts Diluted White Glue
• 1 part Warm Water 
• Large Mixing Bowl
• Spatula or Wooden Spoon 

Instructions and procedure

• Gather all the materials and spread a sheet on the work surface.
• Now, pour the glue in the large mixing bowl and beat it well.
• Make a paste, by adding one part warm water to two parts of white glue.
• Mix the ingredients well. Continue stirring them, until there no visible lumps remain.
• If you do not get a soupy mixture, you can add more water to the bowl and mix well.
• The final product should be watery, but with a slight white glue consistency. 

 

PROPERTIES OF PLASTER OF PARIS

• It is fine hygroscopic white powder
• Its melting point is 1630C
• Its density is 2.63 g/cm3
• It sets quickly on mixing with water giving out heat
• Expands slightly on setting

USES

• Because of its property of slight expansion on setting, it is used for filling cracks and holes in plaster
• It is also used for filling cracks and knots in wooden surface before painting polishing
• Plaster of Paris is used in making surgical bandages where movable parts of the body are to be held rigidly in place
• It is used in chalk
• As plaster of Paris has high melting point, it is used for plastering the walls of wooden houses, such as a protection against fire
• It is used for making models and statues